Source attributes in output template (#45)

* Updated download options to take a media item; allowed for specifying custom output path template options

* Fixed bug where indexing job wouldn't run for the first time

* Renamed friendly_name to custom_name

* Added new options to default template and UI

* Improved explainer UI

priv/repo/migrations/20240302194115_rename_friendly_name_to_custom_name.exs

@@ -0,0 +1,7 @@
+defmodule Pinchflat.Repo.Migrations.RenameFriendlyNameToCustomName do
+  use Ecto.Migration
+
+  def change do
+    rename table(:sources), :friendly_name, to: :custom_name
+  end
+end